From bdc807871d58285737d50dc6163d0feb72cb0dc2 Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@zytor.com>
Date: Fri, 8 Feb 2008 04:21:26 -0800
Subject: [PATCH] avoid overflows in kernel/time.c
When the conversion factor between jiffies and milli- or microseconds is
not a single multiply or divide, as for the case of HZ == 300, we currently
do a multiply followed by a divide. The intervening result, however, is
subject to overflows, especially since the fraction is not simplified (for
HZ == 300, we multiply by 300 and divide by 1000).
This is exposed to the user when passing a large timeout to poll(), for
example.
This patch replaces the multiply-divide with a reciprocal multiplication on
32-bit platforms. When the input is an unsigned long, there is no portable
way to do this on 64-bit platforms there is no portable way to do this
since it requires a 128-bit intermediate result (which gcc does support on
64-bit platforms but may generate libgcc calls, e.g. on 64-bit s390), but
since the output is a 32-bit integer in the cases affected, just simplify
the multiply-divide (*3/10 instead of *300/1000).
The reciprocal multiply used can have off-by-one errors in the upper half
of the valid output range. This could be avoided at the expense of having
to deal with a potential 65-bit intermediate result. Since the intent is
to avoid overflow problems and most of the other time conversions are only
semiexact, the off-by-one errors were considered an acceptable tradeoff.
At Ralf Baechle's suggestion, this version uses a Perl script to compute
the necessary constants. We already have dependencies on Perl for kernel
compiles. This does, however, require the Perl module Math::BigInt, which
is included in the standard Perl distribution starting with version 5.8.0.
In order to support older versions of Perl, include a table of canned
constants in the script itself, and structure the script so that
Math::BigInt isn't required if pulling values from said table.
Running the script requires that the HZ value is available from the
Makefile. Thus, this patch also adds the Kconfig variable CONFIG_HZ to the
architectures which didn't already have it (alpha, cris, frv, h8300, m32r,
m68k, m68knommu, sparc, v850, and xtensa.) It does *not* touch the sh or
sh64 architectures, since Paul Mundt has dealt with those separately in the
sh tree.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Ralf Baechle <ralf@linux-mips.org>,
Cc: Sam Ravnborg <sam@ravnborg.org>,
Cc: Paul Mundt <lethal@linux-sh.org>,
Cc: Richard Henderson <rth@twiddle.net>,
Cc: Michael Starvik <starvik@axis.com>,
Cc: David Howells <dhowells@redhat.com>,
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>,
Cc: Hirokazu Takata <takata@linux-m32r.org>,
Cc: Geert Uytterhoeven <geert@linux-m68k.org>,
Cc: Roman Zippel <zippel@linux-m68k.org>,
Cc: William L. Irwin <sparclinux@vger.kernel.org>,
Cc: Chris Zankel <chris@zankel.net>,
Cc: H. Peter Anvin <hpa@zytor.com>,
Cc: Jan Engelhardt <jengelh@computergmbh.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
arch/alpha/Kconfig | 5 +
arch/cris/Kconfig | 4 +
arch/frv/Kconfig | 4 +
arch/h8300/Kconfig | 4 +
arch/m32r/Kconfig | 4 +
arch/m68k/Kconfig | 4 +
arch/m68knommu/Kconfig | 5 +
arch/sparc/Kconfig | 4 +
arch/v850/Kconfig | 7 +
arch/xtensa/Kconfig | 4 +
include/asm-alpha/param.h | 10 +-
include/asm-cris/param.h | 2 +-
include/asm-frv/param.h | 2 +-
include/asm-h8300/param.h | 2 +-
include/asm-m32r/param.h | 2 +-
include/asm-m68k/param.h | 2 +-
include/asm-m68knommu/param.h | 8 +-
include/asm-sparc/param.h | 2 +-
include/asm-v850/anna.h | 6 -
include/asm-v850/as85ep1.h | 6 -
include/asm-v850/fpga85e2c.h | 6 -
include/asm-v850/param.h | 3 +-
include/asm-v850/rte_cb.h | 6 -
include/asm-v850/sim.h | 5 -
include/asm-v850/sim85e2.h | 6 -
include/asm-xtensa/param.h | 2 +-
kernel/Makefile | 8 +
kernel/time.c | 29 ++-
kernel/timeconst.pl | 402 ++++++++++++++++++++++++++++++++++
29 files changed, 486 insertions(+), 68 deletions(-)
create mode 100644 kernel/timeconst.pl
diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index d9df913a464d1..5b7dcd5a0e75b 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -615,6 +615,11 @@ config VERBOSE_MCHECK_ON
Take the default (1) unless you want more control or more info.
+config HZ
+ int
+ default 1200 if ALPHA_RAWHIDE
+ default 1024
+
source "drivers/pci/Kconfig"
source "drivers/eisa/Kconfig"
diff --git a/arch/cris/Kconfig b/arch/cris/Kconfig
index 27b082ac7f11e..ff078e60e76da 100644
--- a/arch/cris/Kconfig
+++ b/arch/cris/Kconfig
@@ -55,6 +55,10 @@ config CRIS
bool
default y
+config HZ
+ int
+ default 100
+
source "init/Kconfig"
menu "General setup"
diff --git a/arch/frv/Kconfig b/arch/frv/Kconfig
index 96f7d70f44736..9e561ede0925b 100644
--- a/arch/frv/Kconfig
+++ b/arch/frv/Kconfig
@@ -57,6 +57,10 @@ config ARCH_HAS_ILOG2_U64
bool
default y
+config HZ
+ int
+ default 1000
+
mainmenu "Fujitsu FR-V Kernel Configuration"
source "init/Kconfig"
diff --git a/arch/h8300/Kconfig b/arch/h8300/Kconfig
index b4ba4f8b505c2..f69e5ea385588 100644
--- a/arch/h8300/Kconfig
+++ b/arch/h8300/Kconfig
@@ -82,6 +82,10 @@ config PCI
bool
default n
+config HZ
+ int
+ default 100
+
source "init/Kconfig"
source "arch/h8300/Kconfig.cpu"
diff --git a/arch/m32r/Kconfig b/arch/m32r/Kconfig
index fe61e00a604f2..d4679ab55b969 100644
--- a/arch/m32r/Kconfig
+++ b/arch/m32r/Kconfig
@@ -38,6 +38,10 @@ config NO_DMA
config ARCH_SUPPORTS_AOUT
def_bool y
+config HZ
+ int
+ default 100
+
source "init/Kconfig"
diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index bcbf3e4ee9d4c..2b0ed89cd1737 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -55,6 +55,10 @@ config NO_DMA
config ARCH_SUPPORTS_AOUT
def_bool y
+config HZ
+ int
+ default 100
+
mainmenu "Linux/68k Kernel Configuration"
source "init/Kconfig"
diff --git a/arch/m68knommu/Kconfig b/arch/m68knommu/Kconfig
index 24f732342d3ed..548a7b321633c 100644
--- a/arch/m68knommu/Kconfig
+++ b/arch/m68knommu/Kconfig
@@ -525,6 +525,11 @@ config 4KSTACKS
running more threads on a system and also reduces the pressure
on the VM subsystem for higher order allocations.
+config HZ
+ int
+ default 1000 if CLEOPATRA
+ default 100
+
comment "RAM configuration"
config RAMBASE
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 08821b078eccc..7c674a3503b66 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -30,6 +30,10 @@ config OF
config ARCH_SUPPORTS_AOUT
def_bool y
+config HZ
+ int
+ default 100
+
source "init/Kconfig"
menu "General machine setup"
diff --git a/arch/v850/Kconfig b/arch/v850/Kconfig
index 225f30d7cb324..7b6d3716efca4 100644
--- a/arch/v850/Kconfig
+++ b/arch/v850/Kconfig
@@ -215,6 +215,13 @@ menu "Processor type and features"
bool
default !V850E_CACHE && !V850E2_CACHE
+ # HZ depends on the platform
+ config HZ
+ int
+ default 24 if V850E_SIM || V850E2_SIM85E2
+ default 122 if V850E2_FPGA85E2C
+ default 100
+
#### Misc config
config ROM_KERNEL
diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index 5d5546ce88fe9..fd36764d7fb72 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -49,6 +49,10 @@ config ARCH_HAS_ILOG2_U64
config NO_IOPORT
def_bool y
+config HZ
+ int
+ default 100
+
source "init/Kconfig"
menu "Processor type and features"
diff --git a/include/asm-alpha/param.h b/include/asm-alpha/param.h
index 214e7996346f2..0982f1d39499f 100644
--- a/include/asm-alpha/param.h
+++ b/include/asm-alpha/param.h
@@ -5,15 +5,7 @@
hardware ignores reprogramming. We also need userland buy-in to the
change in HZ, since this is visible in the wait4 resources etc. */
-
-#ifndef HZ
-# ifndef CONFIG_ALPHA_RAWHIDE
-# define HZ 1024
-# else
-# define HZ 1200
-# endif
-#endif
-
+#define HZ CONFIG_HZ
#define USER_HZ HZ
#define EXEC_PAGESIZE 8192
diff --git a/include/asm-cris/param.h b/include/asm-cris/param.h
index b249726398320..0e47994e40be5 100644
--- a/include/asm-cris/param.h
+++ b/include/asm-cris/param.h
@@ -3,7 +3,7 @@
/* Currently we assume that HZ=100 is good for CRIS. */
#ifdef __KERNEL__
-# define HZ 100 /* Internal kernel timer frequency */
+# define HZ CONFIG_HZ /* Internal kernel timer frequency */
# define USER_HZ 100 /* .. some user interfaces are in "ticks" */
# define CLOCKS_PER_SEC (USER_HZ) /* like times() */
#endif
diff --git a/include/asm-frv/param.h b/include/asm-frv/param.h
index 365653b1726c1..6859dd503ed36 100644
--- a/include/asm-frv/param.h
+++ b/include/asm-frv/param.h
@@ -2,7 +2,7 @@
#define _ASM_PARAM_H
#ifdef __KERNEL__
-#define HZ 1000 /* Internal kernel timer frequency */
+#define HZ CONFIG_HZ /* Internal kernel timer frequency */
#define USER_HZ 100 /* .. some user interfaces are in "ticks" */
#define CLOCKS_PER_SEC (USER_HZ) /* like times() */
#endif
diff --git a/include/asm-h8300/param.h b/include/asm-h8300/param.h
index c25806ed1fb36..04f64f1003792 100644
--- a/include/asm-h8300/param.h
+++ b/include/asm-h8300/param.h
@@ -3,7 +3,7 @@
#ifndef HZ
-#define HZ 100
+#define HZ CONFIG_HZ
#endif
#ifdef __KERNEL__
diff --git a/include/asm-m32r/param.h b/include/asm-m32r/param.h
index 3e14026e39cda..94c7701960483 100644
--- a/include/asm-m32r/param.h
+++ b/include/asm-m32r/param.h
@@ -2,7 +2,7 @@
#define _ASM_M32R_PARAM_H
#ifdef __KERNEL__
-# define HZ 100 /* Internal kernel timer frequency */
+# define HZ CONFIG_HZ /* Internal kernel timer frequency */
# define USER_HZ 100 /* .. some user interfaces are in "ticks" */
# define CLOCKS_PER_SEC (USER_HZ) /* like times() */
#endif
diff --git a/include/asm-m68k/param.h b/include/asm-m68k/param.h
index 60f409d816581..536a27888358d 100644
--- a/include/asm-m68k/param.h
+++ b/include/asm-m68k/param.h
@@ -2,7 +2,7 @@
#define _M68K_PARAM_H
#ifdef __KERNEL__
-# define HZ 100 /* Internal kernel timer frequency */
+# define HZ CONFIG_HZ /* Internal kernel timer frequency */
# define USER_HZ 100 /* .. some user interfaces are in "ticks" */
# define CLOCKS_PER_SEC (USER_HZ) /* like times() */
#endif
diff --git a/include/asm-m68knommu/param.h b/include/asm-m68knommu/param.h
index 4c9904d6512ed..96c4510183249 100644
--- a/include/asm-m68knommu/param.h
+++ b/include/asm-m68knommu/param.h
@@ -1,13 +1,7 @@
#ifndef _M68KNOMMU_PARAM_H
#define _M68KNOMMU_PARAM_H
-
-#if defined(CONFIG_CLEOPATRA)
-#define HZ 1000
-#endif
-#ifndef HZ
-#define HZ 100
-#endif
+#define HZ CONFIG_HZ
#ifdef __KERNEL__
#define USER_HZ HZ
diff --git a/include/asm-sparc/param.h b/include/asm-sparc/param.h
index beaf02d364f23..86ba59af9d2c7 100644
--- a/include/asm-sparc/param.h
+++ b/include/asm-sparc/param.h
@@ -3,7 +3,7 @@
#define _ASMSPARC_PARAM_H
#ifdef __KERNEL__
-# define HZ 100 /* Internal kernel timer frequency */
+# define HZ CONFIG_HZ /* Internal kernel timer frequency */
# define USER_HZ 100 /* .. some user interfaces are in "ticks" */
# define CLOCKS_PER_SEC (USER_HZ)
#endif
diff --git a/include/asm-v850/anna.h b/include/asm-v850/anna.h
index 3be77d5ecfce3..cd5eaee103b0f 100644
--- a/include/asm-v850/anna.h
+++ b/include/asm-v850/anna.h
@@ -134,10 +134,4 @@ extern void anna_uart_pre_configure (unsigned chan,
#define V850E_TIMER_D_TMCD_CS_MIN 1 /* min 2^1 divider */
-/* For <asm/param.h> */
-#ifndef HZ
-#define HZ 100
-#endif
-
-
#endif /* __V850_ANNA_H__ */
diff --git a/include/asm-v850/as85ep1.h b/include/asm-v850/as85ep1.h
index 659bc910ffd72..5a5ca9073d093 100644
--- a/include/asm-v850/as85ep1.h
+++ b/include/asm-v850/as85ep1.h
@@ -149,10 +149,4 @@ extern void as85ep1_uart_pre_configure (unsigned chan,
#define V850E_TIMER_D_TMCD_CS_MIN 2 /* min 2^2 divider */
-/* For <asm/param.h> */
-#ifndef HZ
-#define HZ 100
-#endif
-
-
#endif /* __V850_AS85EP1_H__ */
diff --git a/include/asm-v850/fpga85e2c.h b/include/asm-v850/fpga85e2c.h
index d32f04504b135..23aae666c718c 100644
--- a/include/asm-v850/fpga85e2c.h
+++ b/include/asm-v850/fpga85e2c.h
@@ -79,10 +79,4 @@ extern char _r0_ram;
#endif
-/* For <asm/param.h> */
-#ifndef HZ
-#define HZ 122 /* actually, 8.192ms ticks =~ 122.07 */
-#endif
-
-
#endif /* __V850_FPGA85E2C_H__ */
diff --git a/include/asm-v850/param.h b/include/asm-v850/param.h
index 3c65bd573782d..2818326902905 100644
--- a/include/asm-v850/param.h
+++ b/include/asm-v850/param.h
@@ -23,8 +23,7 @@
#define MAXHOSTNAMELEN 64 /* max length of hostname */
#ifdef __KERNEL__
-#include <asm/machdep.h> /* For HZ */
-
+# define HZ CONFIG_HZ
# define USER_HZ 100
# define CLOCKS_PER_SEC USER_HZ
#endif
diff --git a/include/asm-v850/rte_cb.h b/include/asm-v850/rte_cb.h
index e85d261b79bf0..db9879f00aa7b 100644
--- a/include/asm-v850/rte_cb.h
+++ b/include/asm-v850/rte_cb.h
@@ -69,12 +69,6 @@
#endif /* CONFIG_RTE_MB_A_PCI */
-/* For <asm/param.h> */
-#ifndef HZ
-#define HZ 100
-#endif
-
-
#ifndef __ASSEMBLY__
extern void rte_cb_early_init (void);
extern void rte_cb_init_irqs (void);
diff --git a/include/asm-v850/sim.h b/include/asm-v850/sim.h
index 10236abbe9be7..026932d476cd9 100644
--- a/include/asm-v850/sim.h
+++ b/include/asm-v850/sim.h
@@ -40,11 +40,6 @@
#define R0_RAM_ADDR 0xFFFFF000
-/* For <asm/param.h> */
-#ifndef HZ
-#define HZ 24 /* Minimum supported frequency. */
-#endif
-
/* For <asm/irq.h> */
#define NUM_CPU_IRQS 6
diff --git a/include/asm-v850/sim85e2.h b/include/asm-v850/sim85e2.h
index 17dd4fa318e65..8b4d6974066c2 100644
--- a/include/asm-v850/sim85e2.h
+++ b/include/asm-v850/sim85e2.h
@@ -66,10 +66,4 @@
#define R0_RAM_ADDR 0xFFFFE000
-/* For <asm/param.h> */
-#ifndef HZ
-#define HZ 24 /* Minimum supported frequency. */
-#endif
-
-
#endif /* __V850_SIM85E2_H__ */
diff --git a/include/asm-xtensa/param.h b/include/asm-xtensa/param.h
index ce3a336cad07c..82ad34d92d359 100644
--- a/include/asm-xtensa/param.h
+++ b/include/asm-xtensa/param.h
@@ -12,7 +12,7 @@
#define _XTENSA_PARAM_H
#ifdef __KERNEL__
-# define HZ 100 /* internal timer frequency */
+# define HZ CONFIG_HZ /* internal timer frequency */
# define USER_HZ 100 /* for user interfaces in "ticks" */
# define CLOCKS_PER_SEC (USER_HZ) /* frequnzy at which times() counts */
#endif
diff --git a/kernel/Makefile b/kernel/Makefile
index 60cd39c84e6d4..6c584c55a6e9e 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -91,3 +91,11 @@ quiet_cmd_ikconfiggz = IKCFG $@
targets += config_data.h
$(obj)/config_data.h: $(obj)/config_data.gz FORCE
$(call if_changed,ikconfiggz)
+
+$(obj)/time.o: $(obj)/timeconst.h
+
+quiet_cmd_timeconst = TIMEC $@
+ cmd_timeconst = $(PERL) $< $(CONFIG_HZ) > $@
+targets += timeconst.h
+$(obj)/timeconst.h: $(src)/timeconst.pl FORCE
+ $(call if_changed,timeconst)
diff --git a/kernel/time.c b/kernel/time.c
index 3b705ecc3fb78..a5ec013b6c807 100644
--- a/kernel/time.c
+++ b/kernel/time.c
@@ -39,6 +39,8 @@
#include <asm/uaccess.h>
#include <asm/unistd.h>
+#include "timeconst.h"
+
/*
* The timezone where the local system is located. Used as a default by some
* programs who obtain this value by using gettimeofday.
@@ -93,7 +95,8 @@ asmlinkage long sys_stime(time_t __user *tptr)
#endif /* __ARCH_WANT_SYS_TIME */
-asmlinkage long sys_gettimeofday(struct timeval __user *tv, struct timezone __user *tz)
+asmlinkage long sys_gettimeofday(struct timeval __user *tv,
+ struct timezone __user *tz)
{
if (likely(tv != NULL)) {
struct timeval ktv;
@@ -118,7 +121,7 @@ asmlinkage long sys_gettimeofday(struct timeval __user *tv, struct timezone __us
* hard to make the program warp the clock precisely n hours) or
* compile in the timezone information into the kernel. Bad, bad....
*
- * - TYT, 1992-01-01
+ * - TYT, 1992-01-01
*
* The best thing to do is to keep the CMOS clock in universal time (UTC)
* as real UNIX machines always do it. This avoids all headaches about
@@ -240,7 +243,11 @@ unsigned int inline jiffies_to_msecs(const unsigned long j)
#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
return (j + (HZ / MSEC_PER_SEC) - 1)/(HZ / MSEC_PER_SEC);
#else
- return (j * MSEC_PER_SEC) / HZ;
+# if BITS_PER_LONG == 32
+ return ((u64)HZ_TO_MSEC_MUL32 * j) >> HZ_TO_MSEC_SHR32;
+# else
+ return (j * HZ_TO_MSEC_NUM) / HZ_TO_MSEC_DEN;
+# endif
#endif
}
EXPORT_SYMBOL(jiffies_to_msecs);
@@ -252,7 +259,11 @@ unsigned int inline jiffies_to_usecs(const unsigned long j)
#elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC)
return (j + (HZ / USEC_PER_SEC) - 1)/(HZ / USEC_PER_SEC);
#else
- return (j * USEC_PER_SEC) / HZ;
+# if BITS_PER_LONG == 32
+ return ((u64)HZ_TO_USEC_MUL32 * j) >> HZ_TO_USEC_SHR32;
+# else
+ return (j * HZ_TO_USEC_NUM) / HZ_TO_USEC_DEN;
+# endif
#endif
}
EXPORT_SYMBOL(jiffies_to_usecs);
@@ -352,7 +363,7 @@ EXPORT_SYMBOL(mktime);
* normalize to the timespec storage format
*
* Note: The tv_nsec part is always in the range of
- * 0 <= tv_nsec < NSEC_PER_SEC
+ * 0 <= tv_nsec < NSEC_PER_SEC
* For negative values only the tv_sec field is negative !
*/
void set_normalized_timespec(struct timespec *ts, time_t sec, long nsec)
@@ -453,12 +464,13 @@ unsigned long msecs_to_jiffies(const unsigned int m)
/*
* Generic case - multiply, round and divide. But first
* check that if we are doing a net multiplication, that
- * we wouldnt overflow:
+ * we wouldn't overflow:
*/
if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
return MAX_JIFFY_OFFSET;
- return (m * HZ + MSEC_PER_SEC - 1) / MSEC_PER_SEC;
+ return ((u64)MSEC_TO_HZ_MUL32 * m + MSEC_TO_HZ_ADJ32)
+ >> MSEC_TO_HZ_SHR32;
#endif
}
EXPORT_SYMBOL(msecs_to_jiffies);
@@ -472,7 +484,8 @@ unsigned long usecs_to_jiffies(const unsigned int u)
#elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC)
return u * (HZ / USEC_PER_SEC);
#else
- return (u * HZ + USEC_PER_SEC - 1) / USEC_PER_SEC;
+ return ((u64)USEC_TO_HZ_MUL32 * u + USEC_TO_HZ_ADJ32)
+ >> USEC_TO_HZ_SHR32;
#endif
}
EXPORT_SYMBOL(usecs_to_jiffies);
diff --git a/kernel/timeconst.pl b/kernel/timeconst.pl
new file mode 100644
index 0000000000000..62b1287932ed4
--- /dev/null
+++ b/kernel/timeconst.pl
@@ -0,0 +1,402 @@
+#!/usr/bin/perl
+# -----------------------------------------------------------------------
+#
+# Copyright 2007 rPath, Inc. - All Rights Reserved
+#
+# This file is part of the Linux kernel, and is made available under
+# the terms of the GNU General Public License version 2 or (at your
+# option) any later version; incorporated herein by reference.
+#
+# -----------------------------------------------------------------------
+#
+
+#
+# Usage: timeconst.pl HZ > timeconst.h
+#
+
+# Precomputed values for systems without Math::BigInt
+# Generated by:
+# timeconst.pl --can 24 32 48 64 100 122 128 200 250 256 300 512 1000 1024 1200
+%canned_values = (
+ 24 => [
+ '0xa6aaaaab','0x2aaaaaa',26,
+ '0xa6aaaaaaaaaaaaab','0x2aaaaaaaaaaaaaa',58,
+ 125,3,
+ '0xc49ba5e4','0x1fbe76c8b4',37,
+ '0xc49ba5e353f7ceda','0x1fbe76c8b439581062',69,
+ 3,125,
+ '0xa2c2aaab','0xaaaa',16,
+ '0xa2c2aaaaaaaaaaab','0xaaaaaaaaaaaa',48,
+ 125000,3,
+ '0xc9539b89','0x7fffbce4217d',47,
+ '0xc9539b8887229e91','0x7fffbce4217d2849cb25',79,
+ 3,125000,
+ ], 32 => [
+ '0xfa000000','0x6000000',27,
+ '0xfa00000000000000','0x600000000000000',59,
+ 125,4,
+ '0x83126e98','0xfdf3b645a',36,
+ '0x83126e978d4fdf3c','0xfdf3b645a1cac0831',68,
+ 4,125,
+ '0xf4240000','0x0',17,
+ '0xf424000000000000','0x0',49,
+ 31250,1,
+ '0x8637bd06','0x3fff79c842fa',46,
+ '0x8637bd05af6c69b6','0x3fff79c842fa5093964a',78,
+ 1,31250,
+ ], 48 => [
+ '0xa6aaaaab','0x6aaaaaa',27,
+ '0xa6aaaaaaaaaaaaab','0x6aaaaaaaaaaaaaa',59,
+ 125,6,
+ '0xc49ba5e4','0xfdf3b645a',36,
+ '0xc49ba5e353f7ceda','0xfdf3b645a1cac0831',68,
+ 6,125,
+ '0xa2c2aaab','0x15555',17,
+ '0xa2c2aaaaaaaaaaab','0x1555555555555',49,
+ 62500,3,
+ '0xc9539b89','0x3fffbce4217d',46,
+ '0xc9539b8887229e91','0x3fffbce4217d2849cb25',78,
+ 3,62500,
+ ], 64 => [
+ '0xfa000000','0xe000000',28,
+ '0xfa00000000000000','0xe00000000000000',60,
+ 125,8,
+ '0x83126e98','0x7ef9db22d',35,
+ '0x83126e978d4fdf3c','0x7ef9db22d0e560418',67,
+ 8,125,
+ '0xf4240000','0x0',18,
+ '0xf424000000000000','0x0',50,
+ 15625,1,
+ '0x8637bd06','0x1fff79c842fa',45,
+ '0x8637bd05af6c69b6','0x1fff79c842fa5093964a',77,
+ 1,15625,
+ ], 100 => [
+ '0xa0000000','0x0',28,
+ '0xa000000000000000','0x0',60,
+ 10,1,
+ '0xcccccccd','0x733333333',35,
+ '0xcccccccccccccccd','0x73333333333333333',67,
+ 1,10,
+ '0x9c400000','0x0',18,
+ '0x9c40000000000000','0x0',50,
+ 10000,1,
+ '0xd1b71759','0x1fff2e48e8a7',45,
+ '0xd1b71758e219652c','0x1fff2e48e8a71de69ad4',77,
+ 1,10000,
+ ], 122 => [
+ '0x8325c53f','0xfbcda3a',28,
+ '0x8325c53ef368eb05','0xfbcda3ac10c9714',60,
+ 500,61,
+ '0xf9db22d1','0x7fbe76c8b',35,
+ '0xf9db22d0e560418a','0x7fbe76c8b43958106',67,
+ 61,500,
+ '0x8012e2a0','0x3ef36',18,
+ '0x8012e29f79b47583','0x3ef368eb04325',50,
+ 500000,61,
+ '0xffda4053','0x1ffffbce4217',45,
+ '0xffda4052d666a983','0x1ffffbce4217d2849cb2',77,
+ 61,500000,
+ ], 128 => [
+ '0xfa000000','0x1e000000',29,
+ '0xfa00000000000000','0x1e00000000000000',61,
+ 125,16,
+ '0x83126e98','0x3f7ced916',34,
+ '0x83126e978d4fdf3c','0x3f7ced916872b020c',66,
+ 16,125,
+ '0xf4240000','0x40000',19,
+ '0xf424000000000000','0x4000000000000',51,
+ 15625,2,
+ '0x8637bd06','0xfffbce4217d',44,
+ '0x8637bd05af6c69b6','0xfffbce4217d2849cb25',76,
+ 2,15625,
+ ], 200 => [
+ '0xa0000000','0x0',29,
+ '0xa000000000000000','0x0',61,
+ 5,1,
+ '0xcccccccd','0x333333333',34,
+ '0xcccccccccccccccd','0x33333333333333333',66,
+ 1,5,
+ '0x9c400000','0x0',19,
+ '0x9c40000000000000','0x0',51,
+ 5000,1,
+ '0xd1b71759','0xfff2e48e8a7',44,
+ '0xd1b71758e219652c','0xfff2e48e8a71de69ad4',76,
+ 1,5000,
+ ], 250 => [
+ '0x80000000','0x0',29,
+ '0x8000000000000000','0x0',61,
+ 4,1,
+ '0x80000000','0x180000000',33,
+ '0x8000000000000000','0x18000000000000000',65,
+ 1,4,
+ '0xfa000000','0x0',20,
+ '0xfa00000000000000','0x0',52,
+ 4000,1,
+ '0x83126e98','0x7ff7ced9168',43,
+ '0x83126e978d4fdf3c','0x7ff7ced916872b020c4',75,
+ 1,4000,
+ ], 256 => [
+ '0xfa000000','0x3e000000',30,
+ '0xfa00000000000000','0x3e00000000000000',62,
+ 125,32,
+ '0x83126e98','0x1fbe76c8b',33,
+ '0x83126e978d4fdf3c','0x1fbe76c8b43958106',65,
+ 32,125,
+ '0xf4240000','0xc0000',20,
+ '0xf424000000000000','0xc000000000000',52,
+ 15625,4,
+ '0x8637bd06','0x7ffde7210be',43,
+ '0x8637bd05af6c69b6','0x7ffde7210be9424e592',75,
+ 4,15625,
+ ], 300 => [
+ '0xd5555556','0x2aaaaaaa',30,
+ '0xd555555555555556','0x2aaaaaaaaaaaaaaa',62,
+ 10,3,
+ '0x9999999a','0x1cccccccc',33,
+ '0x999999999999999a','0x1cccccccccccccccc',65,
+ 3,10,
+ '0xd0555556','0xaaaaa',20,
+ '0xd055555555555556','0xaaaaaaaaaaaaa',52,
+ 10000,3,
+ '0x9d495183','0x7ffcb923a29',43,
+ '0x9d495182a9930be1','0x7ffcb923a29c779a6b5',75,
+ 3,10000,
+ ], 512 => [
+ '0xfa000000','0x7e000000',31,
+ '0xfa00000000000000','0x7e00000000000000',63,
+ 125,64,
+ '0x83126e98','0xfdf3b645',32,
+ '0x83126e978d4fdf3c','0xfdf3b645a1cac083',64,
+ 64,125,
+ '0xf4240000','0x1c0000',21,
+ '0xf424000000000000','0x1c000000000000',53,
+ 15625,8,
+ '0x8637bd06','0x3ffef39085f',42,
+ '0x8637bd05af6c69b6','0x3ffef39085f4a1272c9',74,
+ 8,15625,
+ ], 1000 => [
+ '0x80000000','0x0',31,
+ '0x8000000000000000','0x0',63,
+ 1,1,
+ '0x80000000','0x0',31,
+ '0x8000000000000000','0x0',63,
+ 1,1,
+ '0xfa000000','0x0',22,
+ '0xfa00000000000000','0x0',54,
+ 1000,1,
+ '0x83126e98','0x1ff7ced9168',41,
+ '0x83126e978d4fdf3c','0x1ff7ced916872b020c4',73,
+ 1,1000,
+ ], 1024 => [
+ '0xfa000000','0xfe000000',32,
+ '0xfa00000000000000','0xfe00000000000000',64,
+ 125,128,
+ '0x83126e98','0x7ef9db22',31,
+ '0x83126e978d4fdf3c','0x7ef9db22d0e56041',63,
+ 128,125,
+ '0xf4240000','0x3c0000',22,
+ '0xf424000000000000','0x3c000000000000',54,
+ 15625,16,
+ '0x8637bd06','0x1fff79c842f',41,
+ '0x8637bd05af6c69b6','0x1fff79c842fa5093964',73,
+ 16,15625,
+ ], 1200 => [
+ '0xd5555556','0xd5555555',32,
+ '0xd555555555555556','0xd555555555555555',64,
+ 5,6,
+ '0x9999999a','0x66666666',31,
+ '0x999999999999999a','0x6666666666666666',63,
+ 6,5,
+ '0xd0555556','0x2aaaaa',22,
+ '0xd055555555555556','0x2aaaaaaaaaaaaa',54,
+ 2500,3,
+ '0x9d495183','0x1ffcb923a29',41,
+ '0x9d495182a9930be1','0x1ffcb923a29c779a6b5',73,
+ 3,2500,
+ ]
+);
+
+$has_bigint = eval 'use Math::BigInt qw(bgcd); 1;';
+
+sub bint($)
+{
+ my($x) = @_;
+ return Math::BigInt->new($x);
+}
+
+#
+# Constants for division by reciprocal multiplication.
+# (bits, numerator, denominator)
+#
+sub fmul($$$)
+{
+ my ($b,$n,$d) = @_;
+
+ $n = bint($n);
+ $d = bint($d);
+
+ return scalar (($n << $b)+$d-bint(1))/$d;
+}
+
+sub fadj($$$)
+{
+ my($b,$n,$d) = @_;
+
+ $n = bint($n);
+ $d = bint($d);
+
+ $d = $d/bgcd($n, $d);
+ return scalar (($d-bint(1)) << $b)/$d;
+}
+
+sub fmuls($$$) {
+ my($b,$n,$d) = @_;
+ my($s,$m);
+ my($thres) = bint(1) << ($b-1);
+
+ $n = bint($n);
+ $d = bint($d);
+
+ for ($s = 0; 1; $s++) {
+ $m = fmul($s,$n,$d);
+ return $s if ($m >= $thres);
+ }
+ return 0;
+}
+
+# Provides mul, adj, and shr factors for a specific
+# (bit, time, hz) combination
+sub muladj($$$) {
+ my($b, $t, $hz) = @_;
+ my $s = fmuls($b, $t, $hz);
+ my $m = fmul($s, $t, $hz);
+ my $a = fadj($s, $t, $hz);
+ return ($m->as_hex(), $a->as_hex(), $s);
+}
+
+# Provides numerator, denominator values
+sub numden($$) {
+ my($n, $d) = @_;
+ my $g = bgcd($n, $d);
+ return ($n/$g, $d/$g);
+}
+
+# All values for a specific (time, hz) combo
+sub conversions($$) {
+ my ($t, $hz) = @_;
+ my @val = ();
+
+ # HZ_TO_xx
+ push(@val, muladj(32, $t, $hz));
+ push(@val, muladj(64, $t, $hz));
+ push(@val, numden($t, $hz));
+
+ # xx_TO_HZ
+ push(@val, muladj(32, $hz, $t));
+ push(@val, muladj(64, $hz, $t));
+ push(@val, numden($hz, $t));
+
+ return @val;
+}
+
+sub compute_values($) {
+ my($hz) = @_;
+ my @val = ();
+ my $s, $m, $a, $g;
+
+ if (!$has_bigint) {
+ die "$0: HZ == $hz not canned and ".
+ "Math::BigInt not available\n";
+ }
+
+ # MSEC conversions
+ push(@val, conversions(1000, $hz));
+
+ # USEC conversions
+ push(@val, conversions(1000000, $hz));
+
+ return @val;
+}
+
+sub output($@)
+{
+ my($hz, @val) = @_;
+ my $pfx, $bit, $suf, $s, $m, $a;
+
+ print "/* Automatically generated by kernel/timeconst.pl */\n";
+ print "/* Conversion constants for HZ == $hz */\n";
+ print "\n";
+ print "#ifndef KERNEL_TIMECONST_H\n";
+ print "#define KERNEL_TIMECONST_H\n";
+ print "\n";
+
+ print "#include <linux/param.h>\n";
+
+ print "\n";
+ print "#if HZ != $hz\n";
+ print "#error \"kernel/timeconst.h has the wrong HZ value!\"\n";
+ print "#endif\n";
+ print "\n";
+
+ foreach $pfx ('HZ_TO_MSEC','MSEC_TO_HZ',
+ 'USEC_TO_HZ','HZ_TO_USEC') {
+ foreach $bit (32, 64) {
+ foreach $suf ('MUL', 'ADJ', 'SHR') {
+ printf "#define %-23s %s\n",
+ "${pfx}_$suf$bit", shift(@val);
+ }
+ }
+ foreach $suf ('NUM', 'DEN') {
+ printf "#define %-23s %s\n",
+ "${pfx}_$suf", shift(@val);
+ }
+ }
+
+ print "\n";
+ print "#endif /* KERNEL_TIMECONST_H */\n";
+}
+
+($hz) = @ARGV;
+
+# Use this to generate the %canned_values structure
+if ($hz eq '--can') {
+ shift(@ARGV);
+ @hzlist = sort {$a <=> $b} (@ARGV);
+
+ print "# Precomputed values for systems without Math::BigInt\n";
+ print "# Generated by:\n";
+ print "# timeconst.pl --can ", join(' ', @hzlist), "\n";
+ print "\%canned_values = (\n";
+ my $pf = "\t";
+ foreach $hz (@hzlist) {
+ my @values = compute_values($hz);
+ print "$pf$hz => [\n";
+ while (scalar(@values)) {
+ my $bit;
+ foreach $bit (32, 64) {
+ my $m = shift(@values);
+ my $a = shift(@values);
+ my $s = shift(@values);
+ print "\t\t\'",$m,"\',\'",$a,"\',",$s,",\n";
+ }
+ my $n = shift(@values);
+ my $d = shift(@values);
+ print "\t\t",$n,',',$d,",\n";
+ }
+ print "\t]";
+ $pf = ', ';
+ }
+ print "\n);\n";
+} else {
+ $hz += 0; # Force to number
+ if ($hz < 1) {
+ die "Usage: $0 HZ\n";
+ }
+
+ @val = @{$canned_values{$hz}};
+ if (!defined(@val)) {
+ @val = compute_values($hz);
+ }
+ output($hz, @val);
+}
+exit 0;
--
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